Biomechanics of lateral plate and pedicle screw constructs in lumbar spines instrumented at two levels with laterally placed interbody cages

Nayak, Aniruddh N.; Gutiérrez, Sergio; Billys, James B.; Santoni, Brandon G.; Castellvi, Antonio E.

doi:10.1016/j.spinee.2013.03.048

Cited by 31 publications

(35 citation statements)

References 19 publications

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“…The results of the present study extend previous experimental mechanical analysis of interbody fusion cages that address the overall behavior of the vertebral-cage complex or large spine segments (Coe et al, 1989; Nayak et al, 2013; Rapoff et al, 1997; Wang et al, 2014). Previous experimental biomechanical studies of cages measure platen-to-platen deformation and thus describe relative changes in construct rotational or flexural stiffness, but not the actual mechanical properties or behavior of the cage.…”

Section: Discussionsupporting

confidence: 79%

“…These approaches would yield only overall deformation and be difficult to affix to individual and internal struts. Imaging with x-ray or fluoroscopy are often employed to determine the position of spine cages (Burkus et al, 2002a; Nayak et al, 2013). Such imaging methods, along with image analyses such as texture analysis, can delineate bone deformation in vitro to a resolution of 1.23 μm and strain of 300 με during physiological loading (Bay et al, 1999a, 1999b).…”

Section: Introductionmentioning

confidence: 99%

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Ex vivo loading of trussed implants for spine fusion induces heterogeneous strains consistent with homeostatic bone mechanobiology

Caffrey

Cory

Wong

et al. 2016

Journal of Biomechanics

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A truss structure was recently introduced as an interbody fusion cage. As a truss system, some of the connected elements may be in a state of compression and others in tension. This study aimed to quantify both the mean and variance of strut strains in such an implant when loaded in a simulated fusion condition with vertebral body or contoured plastic loading platens ex vivo. Cages were each instrumented with 78 fiducial spheres, loaded between platens (vertebral body or contoured plastic), imaged using high resolution micro-CT, and analyzed for deformation and strain of each of the 221 struts. With repeated loading of a cage by vertebral platens, the distribution (variance, indicated by SD) of strut strains widened from 50 N control (4 ± 114 με, mean ± SD) to 1000 N (−23 ± 273 με) and 2000 N (−48 ± 414 με), and between 1000 N and 2000 N. With similar loading of multiple cages, the strain distribution at 2000 N (23 ± 389 με) increased from 50 N control. With repeated loading by contoured plastic platens, induced strains at 2000 N had a distribution similar to that induced by vertebral platens (84 ± 426 με). In all studies, cages exhibited increases in strut strain amplitude when loaded from 50 N to 1000 N or 2000 N. Correspondingly, at 2000 N, 59–64% of struts exhibited strain amplitudes consistent with mechanobiologically-regulated bone homeostasis. At 2000 N, vertically-oriented struts exhibited deformation of −2.87 ± 2.04 μm and strain of −199 ± 133 με, indicating overall cage compression. Thus, using an ex vivo 3-D experimental biomechanical analysis method, a truss implant can have strains induced by physiological loading that are heterogeneous and of amplitudes consistent with mechanobiological bone homeostasis.

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Section: Discussionsupporting

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Ex vivo loading of trussed implants for spine fusion induces heterogeneous strains consistent with homeostatic bone mechanobiology

Caffrey

Cory

Wong

et al. 2016

Journal of Biomechanics

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“…In a separate biomechanical study, we demonstrated that pedicle screw and rod instrumentation provided the best limitation to motion of the spinal segments [15]. While important in ascribing acute efficacy to the lateral transpsoas approach to fusion, these basic science studies could not determine whether the noted radiographic changes would result in longitudinal relief of pain and restoration of function.…”

Section: Introductionmentioning

confidence: 90%

“…Reduction of the spinal deformities has been shown to increase the foraminal and central canal area [16]. Once indirect decompression is accomplished, the cages can be used in stand-alone fashion [5,16] or with supplemental instrumentation such as percutaneous pedicle screws, which confer maximum stability to the affected segment [3,15]. Both the indirect decompression and percutaneous pedicle screws are accepted minimally invasive surgical (MIS) techniques that require little soft tissue dissection and minimal blood loss.…”

Section: Introductionmentioning

confidence: 99%

Indirect Decompression of Lumbar Stenosis With Transpsoas Interbody Cages and Percutaneous Posterior Instrumentation

Castellvi

Nienke

Marulanda

et al. 2014

Clinical Orthopaedics &Amp; Related Research

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Background The minimally invasive lateral transpsoas retroperitoneal approach to address lumbar stenosis offers advantages to traditional approaches, including sparing of the AP annulus and longitudinal ligament and less risk to the peritoneal contents and retroperitoneal vascular structures. Few studies have presented longitudinal measures of radiographic indirect decompression and relief of pain and restoration of function using the lateral approach to spine fusion. Question/purposes We determined (1) whether radiographic measures suggestive of decompression were achieved after surgery and maintained 1 year after surgery, (2) whether the intervention resulted in sustained improvements in patient-reported outcomes scores 1 year after surgery, and (3) the frequency of pseudarthrosis on CT scans at 1 year after surgery in patients with moderate or severe lumbar stenosis treated with the approach. Methods Between 2008 and 2012, 158 patients were surgically treated to alleviate symptoms associated with degenerative lumbar stenosis, of whom 60 (38%) were treated with lateral lumbar interbody fusion. Of these 60 patients, 36 (60%) received CT scans preoperatively and at 1-year postoperatively and were available for radiographic analysis. Of the 60 treated patients, 16 (27%) were lost to followup before 12 months, leaving the records of 44 patients available for review of patient-reported improvements in pain and return to function. Radiographic increases in disc height, foraminal area, and canal area were measured by one observer on CT scans postoperatively and at 1 year and compared to preoperative values. Patient-reported scores, including VAS pain score and Oswestry Disability Index (ODI), were collected preoperatively and at 3 and 12 months postoperatively.

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“…4,[10][11][12][13][14][15] Mechanistically, the pure moment is applied to the end vertebrae ensuring equal loading to all segments of the spinal column, 1 even as the spine deforms during testing. This has been accomplished in multiple forms with varying complexity and ease of use, including cable and pulley systems, 2,11,13 in which load application is assisted with static weights or load frame actuation, motor-actuated robotic arms, [15][16][17] and hydraulicallyor pneumatically-actuated gimbal systems 10,12,18 that can be configured to apply pure moments at one or both ends of the spinal segment. Stepwise moment application using cable and pulley systems has been the predominant method of flexibility testing 19,20 and is still prevalent in the current literature.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Intervertebral ROM in Multi-Level Cadaveric Lumbar Spines Using Distinct Pure Moment Loading Approaches

et al. 2015

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To our knowledge, this is the first study comparing ROM of multi-segment lumbar spines between laboratories utilizing different apparatuses. The results of this study show that intervertebral ROM in multi-segment lumbar spine constructs are markedly similar in FE loading. Differences in boundary conditions are likely the source of small and sometimes statistically significant differences between the two techniques in LB and AT ROM. The relative merits of each testing strategy with regard to the physiologic conditions that are to be simulated should be considered in the design of a study including LB and AT modes of loading. An understanding of these differences also serves as important information when comparing study results across different laboratories.

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Biomechanics of lateral plate and pedicle screw constructs in lumbar spines instrumented at two levels with laterally placed interbody cages

Cited by 31 publications

References 19 publications

Ex vivo loading of trussed implants for spine fusion induces heterogeneous strains consistent with homeostatic bone mechanobiology

Ex vivo loading of trussed implants for spine fusion induces heterogeneous strains consistent with homeostatic bone mechanobiology

Indirect Decompression of Lumbar Stenosis With Transpsoas Interbody Cages and Percutaneous Posterior Instrumentation

Comparison of Intervertebral ROM in Multi-Level Cadaveric Lumbar Spines Using Distinct Pure Moment Loading Approaches

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